A mesh woven product called “screen mesh” produced by weaving a monofilament has been widely used in the fast-growing field of electronics as a mesh cloth for screen printing in printed circuit boards, and also as a shaped filter used in automobiles and home appliances. Exemplary applications of the mesh woven product produced by weaving a monofilament in the application of screen printing include T shirts and flags, signboards, plates of vending machines, car panels, signs in the interior or exterior, ballpoint pens, various cards, name plates, scratch cards, braille, CDs and DVDs, printed boards, plasma displays, and liquid crystal displays. Exemplary applications in the filter applications include lint filters that prevent reattachment of lint in water to laundry, filters in the air conditioner that remove dust in the room, and shaped filters in vacuum cleaners that remove dust and trash. Exemplary applications in medical field include a filter that removes bubbles and the like in blood infusion kits or artificial dialysis circuits. The mesh woven product also plays an important role in automobile applications including use in fuel flow passages such as fuel pumps and fuel injectors as well as ABS, brakes, transmissions, and power steering, and also, for prevention of foreign substances from entering into electromagnetic valves as well as filtration and cleaning in electronic stability control and VVT and other oil hydraulic circuits that are the latest fuel consumption improving mechanisms.
Of these, in the fields of electronics and automobiles which are in rapid growth, there is a demand for the mesh woven products having a higher performance including clearer printing performance and higher filter performance. Accordingly, mesh woven products having reduced weight and reduced thickness have been developed, and these products are required to have a higher quality. This in turn means that there is a demand for a monofilament having consistent quality with no fineness inconsistency, lumps, tight picks, vertical lines or the like. In view of such a situation, many technologies have been proposed as technologies to improve the quality of monofilaments.
For example, Japanese Unexamined Patent Publication (Kokai) No. 2010-222112 proposes controlling the kinetic friction coefficient of the yarn and take up width of the drum in a drum-shaped package form of polyamide monofilament.
International Publication WO 2011/086954 proposes controlling the kinetic friction coefficient of the yarn, taper angle of the package end, gradient of unwinding tension fluctuation, and shrinkage stress in wet heating of the inner layer of the polyester monofilament at 1 mm interior of the package in a package of a wound polyester monofilament.
While the method described in Japanese Unexamined Patent Publication (Kokai) No. 2010-222112 attempts to improve the quality for a defect called “tight pick” associated with the use of the weft, the problem of the quality relating to the defect called “vertical line” associated with the use of the warp has been left unsolved.
We found that vertical lines are caused by the high tension of the yarn upon passage of the yarn guide in the warping that leaves strain in the yarn and large fluctuation of the tension that unstabilizes the stretching of the yarn. Accordingly, we focused on reducing the tension upon passage of the yarn guide and also, on reducing the fluctuation of the tension. To reduce the fluctuation, the silicon-added oil described in International Publication WO 2011/086954 was applied to the polyamide monofilament.
Nonetheless, while the method described in International Publication WO 2011/086954 reduces the tension upon passage of the yarn guide in the warping, static electricity was generated between the moving yarn and the yarn guide resulting in the yarn adhesion and the like and stable warping became difficult. Under such a situation, decreases in the warping speed were required to suppress the static electricity generation, and this invited loss of weaving productivity. Accordingly, further improvement has been necessary.
It could therefore be helpful to provide a polyamide monofilament that exhibits low tension and reduces static electricity generation when the yarn is passed through a yarn guide in the warping to thereby enable production of a mesh woven product with excellent quality as well as high weaving productivity. It could also be helpful to provide its fiber package.